Predator-prey ratio and guild constancy in a tropical insect community

An analysis of predator-prey ratio and guild constancy was made for 41 099 insects from 31 Acacia tree canopies in north-east Tanzania. A strong proportionality between predator-prey species richness, abundance and biomass was found, with reduced major axis slopes not statistically different from one. Predictions of five existing hypotheses to account for predator-prey ratios were tested: the energy ratio and common determinants of diversity hypotheses were well supported and most likely to explain the pattern reported here. Since predator-prey ratios can be considered a special case of the general guild constancy problem, it was also investigated whether species and biomass shares of guilds differed between six tree species and nine sampling localities. For most guilds no significant differences were found and both energy ratio and common determinants of diversity hypotheses might explain the observed general pattern of resource division in this ecological community.